Devices for detecting the presence of ice on structures, for example aircraft structures, are known. Example devices include those that detect ice formation using optical means (i.e. detecting a change in opacity or refractive index around a sensor). Others include those that monitor changes in a resonant frequency of a structure (i.e. the accumulation of ice on a structure alters its resonant frequency).
We have appreciated the disadvantages of known devices for detecting the presence of ice, and the need for an improved device.